The invention relates to devices for audibly signalling or alerting in response to light and, more particularly, to self-contained, portable devices of such character which are responsive to receiving light upon the occurrence of an event to be detected.
Within a typical household where there are young children, a medicine cabinet and other normally darkened enclosures having easily opened doors are typically used for storage of medicines, drugs and other poisonous or potentially dangerous substances or items.
It is often desirable for a parent or other person responsible for such a child in this kind of an environment to know if the child should open an enclosure containing a substance or other item which could be injurious to the child.
However, it is often difficult, if not impossible, to closely monitor the activities of a normally inquisitive child within the home. Accordingly, to prevent a child from opening an unlocked enclosure containing potentially injurious substances or items is not practically attainable.
Of course, it would be possible to install burglar alarm-type sensors, such as door-operated switches wired to an alarm, but this is usually prohibitively complex and expensive.
One difficulty in utilizing an audible alerting signal for warning persons in these situations is that the signal must be heard at a considerable distance from the guarded location and desirably should command one's attention as well as be capable of being heard by those having impaired hearing.